With the increasing sophistication of office equipment, such as digital copiers, printers, facsimiles, as well as devices which combine many of these functions, individual devices become more and more software intensive. Much of the functionality associated with a particular device dwells in the software of the device, and functionalities of a device can be improved or increased by a software upgrade. Preferably, such software upgrades could be performed by direct installation of new software into a memory within the device. This software installation could be performed, for example, by a tech rep attending the device and plugging in a personal computer or laptop into the device for direct downloading of software; or, the software could be installed in a device remotely, over a network.
Generally, with digital office equipment, the mechanical interfaces between machines and between a device on a network should be of one of a relatively small number of standard designs. The most common design for digital printers is known as the "Centronics" port, which is a type of parallel port having a certain number of pins. When a Centronics port is used to convey data to be printed from a computer to a digital printer, the pins in the port are each given specific functions. For instance, in one typical arrangement, eight pins of the port are dedicated to conveying 8-bit parallel image-related data from the computer to the printer; simultaneously, four pins on the same port are used to convey status information from the printer back to the computer. In a standard design, each of these four pins has a single specific function which is independent of the functions of the other three "status" pins. A typical set of "status bits" used in a standard Centronics interface would include an "out of paper" bit, a "printer not ready" bit, and a "printer error" bit. Whether any of these particular states of the printer was detected by the computer would depend on whether any individual one of these status bits happened to be high.
It is an object of the present invention to provide a system whereby the three standard status lines in a Centronics interface can be expanded to increase the number of possible status messages from a printer to a computer, and thus allow a relatively complicated procedure, such as a software upgrade, to be performed via a standard printer interface port.